Looking toward next-generation mobile communication systems, various studies have been conducted on radio transmission schemes suitable for high-speed packet transmissions, to achieve data rates over 100 Mbps and low delay transmissions to accommodate various traffics.
OFDM (Orthogonal Frequency Division Multiplexing), whereby data is transmitted in parallel using a large number of subcarriers, is becoming a focus of attention in recent years, as a transmission scheme that enables high-speed transmission in a multipath communication environment. Moreover, to achieve low delay transmissions, the use of short TTI's (Transmission Time Intervals) of approximately 0.5 ms, for example, has been studied (see, for example, non-patent document 1). In OFDM, a wireless communication base station apparatus (hereinafter simply “base station”) performs adaptive control including scheduling and adaptive modulation of transmission packets in TTI units, per subcarrier or per subchannel bundling a plurality of subcarriers. By this means, throughput can be significantly improved.    Non-patent Document 1: “Effect of Frequency-domain Packet Scheduling in Forward Link Spread OFDM Broadband Packet Wireless Access” Nagata et al, Technical Report of IEICE, RCS2004-228, November 2004.